Drilling jar

Abstract

A drilling jar to be installed in a set of drill collars in a drill string is disclosed. In the illustrated embodiment, first and second tubular members telescope relative to one another. At the upper end of the lower tubular member, a set of protruding lugs match shoulders having undercuts which permit relative rotation of the two tubular members through part of a turn, thereby permitting the two members to axially telescope whereby locking or unlocking the telescoping movement is controlled. The lower tubular member has an upwardly facing shoulder which is abutted against the lower end of the upper tubular member. This permits the two to be reciprocated and banged together to create a jar for the drill string. When the string is jarred, the drill string can be jarred loose. the apparatus further includes a packer around a pipe positioned in the upper end of the upper tubular member.

I claim: 
     
       1. A drilling jar for use with a drill string to assist in unsticking the drill string, comprising: (a) an upper hollow mandrel having (1) connector means enabling said upper mandrel to be connected into a drill string;   (2) a packer therein for sealing against a member inseated thereinto;   (3) a lower shoulder on said mandrel useable as a hammer;   (4) first and second spaced encircling internal grooves separated by a land in the lower portion of said mandrel;   (5) a transverse shoulder interrupting said grooves;   (6) a transverse groove across said land, said groove cooperating with said land to define a spline rib parallel to the axis of said upper mandrel;     (b) a lower hollow mandrel having (1) an upper stinger pipe axially communicated with said lower mandrel and telescoped into said packer for sliding and sealing movement in said upper mandrel;   (2) an upwardly facing shoulder adopted to be used as an anvil and arranged on said lower mandrel for hammering by said lower shoulder on said upper mandrel;   (3) connector means at the lower end of said lower mandrel enabling said lower mandrel to be connected to the lower portions of a drill string;   (4) a protruding lug extending from said stinger pipe and having a profile such that said lug fits into either of said internal grooves and can rotatably move in said grooves until movement carries against said transverse shoulder whereupon said lug is constrained by said shoulder against further rotation in said grooves on drilling where the drill string turns to the right so that said upper hollow mandrel and said lower hollow mandrel rotate together as a unit; and where said lug is moved away from said transverse shoulder and moves into alignment with said transverse groove wherein said lug has a profile to enable said lug to slidably move along said transverse groove as said upper and lower mandrels are telescoped relative to one another; and   (5) said lug moving between said first and second encircling grooves on telescoping movement wherein the travel of said lug is equal to the stroke of said upper mandrel as it hammers against said lower mandrel to impact a jarring impact to the drill string.     
     
     
       2. The apparatus of claim 1 including N lugs arranged in a circle around said stinger pipe where N is a whole number integer and wherein said transverse shoulders are N in number, and said lugs and said shoulders are arranged at N locations evenly spaced around said stinger pipe. 
     
     
       3. The apparatus of claim 2 wherein said transverse grooves are N in number, and are evenly spaced around said upper mandrel. 
     
     
       4. The apparatus of claim 3 including M sets of lugs evenly spaced from one another along said stinger pipe and wherein M is a whole number integer, and said upper mandrel has at least M + 1 evenly spaced internal grooves which are all similarly constructed with N transverse shoulders. 
     
     
       5. The apparatus of claim 4 including sufficient length on said stinger pipe to permit a stroke of twice the spacing between adjacent spaced internal grooves of said upper mandrel. 
     
     
       6. The apparatus of claim 5 including a first and second threaded portions of said upper mandrel which join and separate adjacent to said packer to enable said upper mandrel to be opened adjacent to said packer to permit access to said packer and wherein said packer includes at least a plurality of seals and a means for compressing said seals. 
     
     
       7. The apparatus of claim 6 including an enlarged axial passage in said upper mandrel for receiving said stinger pipe which enlarged passage extends there along by a length to receive said stinger pipe on its maximum stroke. 
     
     
       8. The apparatus of claim 7 including a narrow passage axially concentric with said enlarged passage. 
     
     
       9. The apparatus of claim 8 including a pin and box connection comprising said connector means on said upper and lower mandrels.